K*(892)电磁质量反常(英文)

电中性的 K* (892 )电磁质量可以大于带电荷的 K* (892 ) .这是异乎寻常的现象 ,将被称为K* -电磁质量反常 .评述了这个课题 ,并指出 K* 的质量劈裂可以在北京谱仪 (BES)上作精密测量. Electromagnetic masses of neutral K *(892) may be larger than one of charged K *(892). It is unusual and is called K *-EM-mass anomaly. We review the studies on this issue, and point out that K *-mass splitting can be measured in BES accurately.     

Breit势的正规化与ηc-J/ψ的劈裂

研究自旋和轨道量子数不同的介子之间的质量劈裂对检验夸克势模型非常重要。 在以往的夸克势模型计算中,η_c-J/ψ的质量劈裂都很难达到实验的值。 用正规化形状因子μ2/(q2+μ2)， 在对完整的动量空间中的Breit夸克势实施一次正规化下研究了η_c-J/ψ和新介子ηb与Υ(1s)之间的质量劈裂。 结果表明， 正规化形状因子中的屏蔽质量μ应与介子折合质量有关， 当将其展开为介子折合质量的三阶多项式时， 上述介子质量劈裂可以精确重现实验的结果。另外， 由于完整的Breit势包含有自旋-轨道耦合相互作用的项，因而还可以研究χc0,χc1和χc2之间的质量劈裂。 The study of the splittings between the masses of mesons with different spin and orbit quantum numbers is important for checking the quark potential model. In the previous calculations with quark potential models, the splitting between ηc and J/ψ is however too small to the experimental result. In this paper the mass splitting of ηc J/ψ and the splitting between the new meson ηb and Υ(1s) are investigated with the complete Breit quark potential regularized by applying the form factor μ2/(q2+μ2) one time in momentum space. In addition, because the complete Breit potential includes the spin orbit interaction, it can be used to investigate the splittings among χc0, χc1 and χc2. The investigated results indicate that the screen mass μ in the form factor of regularization is related to the reduced mass of meson. The splittings of η_c-J/ψ, ηb Υ, and χc0 χc1 χc2 can reproduce the experimental results with high accuracy when the screen mass is expanded to the third order polynomial of meson reduced mass.     

Exotic and excited-state meson spectroscopy and radiative transitions from lattice QCD

We discuss recent progress in extracting the excited meson spectrum and radiative transition form factors from lattice QCD.We mention results in the charmonium sector,including the first lattice QCD calculation of radiative transition rates involving excited charmonium states,highlighting results for high spin and exotic states.We present recent results on a highly excited isovector meson spectrum from dynamical anisotropic lattices.Using carefully constructed operators we show how the continuum spin of extracted states can be reliably identified and confidently extract excited states,states with exotic quantum numbers and states of high spin.This spectrum includes the first spin-four state extracted from lattice QCD.We conclude with some comments on future prospects.     

Ideal Mixing of Scalar Mesons and Hyperon-Nucleon Interactio~

The mixing of scalar mesons is an open problem since their structure is unclear and controversial. By introducing the ideal mixing of scalar mesons, we dynamically investigate the hyperon-nucleon interaction in the ehiral SU （ 3 ） quark model by solving the resonating group method （RGM） equation. The results show that when the ideal mixing of scalar mesons is considered and the mass of a k meson is reduced to near 780 MeV, then the hyperonnucleon scattering data can be reasonably described in the ehiral SU（3） quark model. Hence we find that the experimental mass of the n meson is around 780 MeV, and fo（600） and fo（980） mesons are the ideal mixing of scalar singlet and octet mesons.     

BESIII上η_c衰变到ωω的蒙特卡罗研究

自从J/φ发现以来,粲偶素家族一直是人们研究的热点问题。根据强子螺旋度守恒定则,ηc和Xc1衰变到ωω被高度压低。然而,在2011年BESIII首次精确测量Xc1衰变到ωω的分支比;但是,到目前为止,仍然没有实验组对ηc衰变到ωω进行精确测量。本文通过蒙特卡罗研究ηc衰变到ωω的测量方法,以期给实验测量提供一定的参考。     

Observation of Influence of Nucleons＇ Motion on Kaons Collective Flow in Dense Medium

In order to extract the information of the momentum-dependent interaction of kaons under the extreme condition, the properties of the positively charged kaons produced in a heavy ion collision are studied via a simple model which has an invariable nucleon＇s velocity. Our special attention is focused on the observation of the dependence of the kaon＇s properties on the motion of nucleons in a hot and dense nuclear environment. Starting from two kinds of kaon quasiparticle models defined in transport theories for simulating heavy ion collisions, we calculate the effective mass and potential of the K＋＇s produced in the collisions and find that these properties not only depend closely on the velocity of nucleons but the dependence varies with kaon＇s quasiparticle model. It is clearly shown that the motion of nucleons reduces the momentum of K＋＇s at a given rapidity and thus weakens the rapidity distribution of K＋＇s directed flow in realistic nuclear collisions.     

Status of the Fermilab muon （g-2） experiment

The New Muon （g-2） Collaboration at Fermilab has proposed to measure the anomalous magnetic moment of the muon, αμ, a factor of four better than was done in E821 at the Brookhaven AGS, which obtained αμ = [116592089（63）] × 10^-11 ±0.54 ppm. The last digit of a, is changed from the published value owing to a new value of the ratio of the muon-to-proton magnetic moment that has become available. At present there appears to be a difference between the Standard-Model value and the measured value, at the ≌ 3 standard deviation level when electron-positron annihilation data are used to determine the lowest-order hadronic piece of the Standard Model contribution. The improved experiment, along with further advances in the determination of the hadronic contribution, should clarify this difference. Because of its ability to constrain the interpretation of discoveries made at the LHC, the improved measurement will be of significant value, whatever discoveries may come from the LHC.     

Relative Nonsymmetry Effects of the Super(Generalized) Nonlinear Velocity, Time of a Particle and Its Kinetic Formulae for Followed Body

描述了粒子作高速运动时的超(广义)非线性速度、时间的相对不对称性效应和随体动力学诸公式。不对称性效应能解释次级宇宙线μ介子出现寿命延长的问题；也解释了著名的孪生子佯谬中谁年轻的争论问题。最后建立了随体的粒子动力学诸公式。